Graded exercise testing of mentally retarded adults: A study of feasibility

There is a striking absence of data on the cardiovascular fitness of mentally retarded adults and what limited data are reported reflect field or submaximal laboratory tests. This study sought to develop a protocol that would allow maximal aerobic testing (V̇O(2max) of mentally retarded adults in the laboratory. Of 21 subjects recruited, 17 (eight men and nine women) were successfully tested. Their mean IQ (±SD) was 52.68 ± 16.3; their weight was 149.76 ± 35.3 lbs, height 64.4 ± 4.2 in, and age 29.29 ± 6.6 yr. The testing occurred in three phases: (1) familiarization with the laboratory environs; (2) training to walk on the treadmill and breathe through the respiratory collection system; and (3) data collection via graded exercise testing. The treadmill protocol consisted of walking at 3 mph at 0% grade for two minutes, followed by 3 mph at a 2.5% grade for two minutes. The speed was then held constant at 3 mph and the grade increased 2.5% every minute until exhaustion. Metabolic data were collected every minute using a Beckman MCC cart connected to the subjects through a Hans-Rudolph valve. Heart rates (HR) were collected with a Quinton electrocardiograph. The mean maximal cardiorespiratory data were as follows (±SD): V̇O(2max) = 26.3 ± 8.0 ml·kg^-1·min^-1; HR(max) = 171 ± 14 beats/min; V̇(Emax) = 62.8 ± 21.8 L/min; and respiratory quotient (R) = 1.09 ± .07. The R values obtained were within an acceptable range for valid maximal data. In addition, 15 subjects produced supramaximal work and showed a decline in V̇O₂ during the last minute of exercise. Thus, valid V̇O(2max) data can be obtained in this population using these recommendations: (1) laboratory familiarization; (2) ample training time; (3) providing safety features to ensure subjects do not fall or fear falling; (4) tailoring the protocol to the population; and (5) providing an environment in which the subjects feel they are contributing members. The data show that these subjects exhibit extremely low cardiorespiratory fitness for their age compared with nondisabled persons. This finding agrees with previous studies that relied on field or submaximal tests, which indicates that young mentally retarded adults are substantially deconditioned.